Inclusive charm production at HERA and charm content of the proton

摘要

The authors calculate the contribution to inclusive high transverse momentum (p(sub T)) charm production at HERA (hadron electron ring at large) from the excitation of charm in the photon. At large values of p(sub T) the results of such a calculation, in the structure function language, will be more reliable as it sums the large logs log(p(sub T)(sup 2)/m(sub C)(sup 2)), as opposed to calculating the contribution of the 2(yields)3 subprocesses in fixed order of perturbation theory. They find that this contribution is large and comparable to the contribution from (gamma)g fusion production of charm. Suitable cuts on the rapidity of the 'away-side' large p(sub T) jet allow a very neat separation between the contributions from the excitation process and from pair-production. Including this excitation contribution the authors can reproduce the measured inclusive D(sup *) and (mu) cross-section measured by the ZEUS and H1 collaborations respectively, in a LO calculation.